A recent study out of North Carolina suggests that people with Crohn’s disease who eat more fiber are less likely to flare.

However, many people with Crohn’s disease are instructed by health care providers and other resources to limit or avoid dietary fiber.

So, what gives?

You might recall from last week’s post that fiber is an undigested carbohydrate in the sense that humans do not have the necessary tools to break it down. Therefore it’s available to nourish the trillions of microbes in our intestines. Many of us are familiar with the sometimes embarrassing gas that results from our gut bacteria feeding on fiber, but what’s less obvious are the healthy by-products of their feeding frenzies, including short-chain fatty acids that help fight inflammation.

This current study of roughly 1,600 adults with IBD in remission at baseline suggested that people with Crohn’s disease who regularly ate bran cereals were about half as likely to flare over six months than those who did not eat the cereal. Also, participants with Crohn’s who did not identify as avoiding high-fiber foods were about 40% less likely to flare than fiber avoiders.

These findings are consistent with previous studies that have shown that people with Crohn’s disease who were instructed to eat a fiber-rich diet without processed carbohydrates (e.g. white flour) required fewer Crohn’s-related hospitalizations and surgeries than people who did not receive dietary instruction.

While these results support a possible role for fiber in managing Crohn’s disease, fibrous foods (e.g. fruits, vegetables, beans, legumes, whole grains) can cause gastrointestinal discomfort, diarrhea, and possibly obstructions in people with strictures or narrowing of the GI tract secondary to active inflammation or scar tissue.

Also, it’s impossible to know whether fiber is directly contributing to the desired outcomes in these patients. Are people who feel better just more likely to eat fiber?

Nonetheless, researchers have long suspected that the lack of dietary fiber in industrialized diets might be contributing to the sudden rise in Crohn's disease and ulcerative colitis. Keep in mind that our gut bacteria directly affects our immune system and what we eat directly affects our gut bacteria. Fiber, in particular, supports the growth of beneficial bacteria.

I've worked with thousands of people with Crohn's disease and some can tolerate fibrous foods whereas others cannot. To learn more about fiber and how to include it in your diet, check out my earlier post “How to eat plant foods in spite of GI issues.”